Thermal protection is a vital requirement for power delivery circuits and prevents permanent damage due to prolonged operation at excessive temperatures. In integrated circuits (ICs), especially in power ICs, power dissipation can cause relatively high temperatures. To avoid degradations phenomena when the circuit temperature rises, or in some cases destructive failures of ICs as a result of excessive temperature, it is usually critical to incorporate a dedicated protection circuit to switch off, at least, the power output portion of the integrated circuit and temporarily disable the primarily source of power dissipation.
A thermal protection circuit limits the maximum operation temperature of the power delivery circuit through a temporary thermal shutdown. It provides safeguard by sensing a temperature of the power delivery circuit and automatically shutting down the power delivery circuit, whenever the circuit temperature exceeds a predetermined threshold. A thermal protection circuit subsequently turns the circuit back on after the circuit cools off to a predetermined lower temperature.
The power delivery circuit may oscillate by being turned on and off through the thermal shutdown circuit; however, the frequency of such oscillation is reduced by incorporation of hysteresis in the form of a temperature “range,” which separates the switch-off and the switch-on temperatures.
While the task of thermal protection circuits that are, for example, used in integrated power circuits is to switch off circuit components having a high dissipation power when a defined temperature threshold is exceeded, the abrupt on-off operations of the protection circuits can cause other damages to sensitive circuits or merely not be desirable for other reasons.